The fungus, Chaloropsis sp, produces an extracellular lysozyme that is lytic to Staphylococcus aureus. This enzyme has been isolated, crystallized and partially characterized. This lysozyme differs from egg white lysozyme in that it is an N, 6-O-diacetylmuramidase. It converts living S. aureus cells to protoplasts in hypertonic sucrose solutions by removing their cell walls. Our research objective is to exploit the Chaloropsis lysozyme in studying various aspects of staphylococcal chemistry. These studies include cell wall structure, preparation of protoplasts and cytoplasmic membranes, and the release of enzymes, toxins, antigens and other cellular constituents. The Chalaropsis lysozyme is of interest in its own right because of its similarity to egg white lysozyme whose amino acid sequence and three dimensional structure is known. Long term objectives include determining the amino acid sequence and establishing the three dimensional structure is known. Long term objectives include determining the amino acid sequence and establishing the three dimensional structure of the Chaloropsis lysozyme. Chalaropsis sp. also produces an extracellular ribonuclease which appears to have an absolute specificity for 3'-guanylic acid residues in RNA. This enzyme has been partially purified. Our objective is the complete purification and characterization of this enzyme for possible use in structural studies of nucleic acids. Certain strains of staphylococci produce capsules that confer resistance to phagocytosis and hence increase their virulence. Our objective is to chemically characterize the capsule of S. aureus M and to investigate the mechanism of its biosynthesis, which may aid in predicting the pathogenicity of staphylococcal isolates.